Isvlproveiviemt in chucks



T.' n. ALMo N D.

\ chucks. N0,` 141,978, PatentedAuvgust19J873.

w lll .si n-nmu fifi' PHO PR s THOMAS R. `ALMOND, OF FITOHBURG,MASSACHUSETTS.

IMPROVEMENT IN CHUCKS.

Specification forming part of Letters Patent No. 141,978, dated August19, 1873 application filed July 2, 1873.

To att whom it may concern:

Be it known that I, THOMAS R. ALMOND, oi"

Fitchburg, in the county'of Worcester and State of Massachusetts, haveinvented an Improved Drill-Chuck, of which the following is aspeciiioation:

Figure l is a side view of my improved drillchuck. Fig. 2 is alongitudinal central section of the same. Fig. 3 is a transverse sectionthereof on the line cla, Fig. l. Figs. 4 and 5 are side views of thechuck-jaws.

Similar letters of reference indicate corre spending parts in all thefigures.

This invention relates to a new construction of a drill-chuck, havingfor its object to simplify, as much as possible, the arrangementof theparts and their operation, and thereby to increase the durability of thechuck. The invention principally consists in the use of a series ofjaws, which are partly cylindrical i along their outer faces and concaveon their gripin g or biting faces, and which are, on their outer faces,provided with spiral or bent grooves for the reception of pins thatproject into such grooves from the embracing-shell of the chuck. Thelower ends of the jaws connect by a swivel-joint with a screw thatenters the back of the shell, so that when said screw is turned the jawswill be longitudinally displaced within the shell,and during suchdisplacement, by virtue of their spiral or bent grooves, they vwill beturned to bring their griping-faccs nearer to or farther away from theaxis of the shell, and be thereby adjusted to the exact size of the rodor drill to be held. I prefer to use two pins in the shell for each jaw,and to have two spiral or bent grooves in each jaw, the two pinsprojecting at an angle toward each other of ninety degrees, more orless, so that such pins may also be used for exactly centering the jaws,by being screwed up more or less from one side or the other. I alsoprefer to so shape the spiral or bent grooves of such jaws that there isless curvature in them where the pins enter them for holding the jaws ofa larger drill than where g the pins enter them for holding them inposition for a smaller drill, so as to obtain a greater proportion offorce for holding larger than for holding smaller drills. It will beobserved that, by using these cylindrical jaws in con nection with asimple embracing-shell and adjusting-screw, all the complex deviceshereto- -fore used for supporting and contracting the jaws with springs,wedges, Sie., are dispensed with, and the construction ofthe apparatusis materially simplified, while, at the same time, the most absolutedegree of strength will be obtained.

ln the accompanying drawing, the letter A represents the shell of myimproved chuck, having, at its lower or back end, a female screw-threadfor the reception of a screw,\]3. On the upper part, the shell has onits inner side three or more partlyecylindrical recesses, which areparallel to its axis, and all equal in diameter to each other. Theserecesses are arranged for the reception of three or more jaws, (l G,which jaws are also cylindrical in outline, at least sufficiently so asto fully Jrit the said recesses, as shown in Fig. 3. Those parts of thejaws which face the axis of the shell are made concave, so that when thej aws are ,in the position shown in Fig. 3, with their concave parts allin continuous line, the space between them will be cylindrical, and willbe the largest space that can bc formed betweenv them. The several jawsare grooved transversely at their lower ends, as shown at a in Figs. etand 5, to receive an inwardly-projecting iiange, b, that enters suchgrooves a from the recessed upper end of the screw B. Thus a connectionis established between the screw and the jaws, as shown in Fig. 2, sothat when said screw is turned it will cause the jaws to travel up anddown with it. The outer sides of the jaws C C are provided each with oneor more spiral or bent grooves, d, which are more clearly shown in Figs.et and 5. Into these grooves enter pins e c, which are screwed throughthe shell to enter said grooves, as shown in Fig. 3. When the jaws arelengthwise displacedby the motion of the screw B they will, owing to thespiral grooves and their connection with the pins c of the shell, alsobe turned all equally, because the grooves d are all alike, and when soturned will bring one of their edges nearer to, and the other fartheraway, from the axis of the shell A. Those edges of the jaws that arebrought nearer toward the center of the shell, as indicated by dottedlines in Fig. 3, constitute the gripmgsurfaces of the chuck, and bearagainst the drill or vspindle introduced between them. The more, byturning the screws, the jaws are raisedTthat is to say, made to projectout of the shell-the more will they be turned to iit and hold a smallerdrill or spindle. The grooves d are, by preference, made straightertoward their upper ends, and inore spiral or bent at their lower parts,as is shown in Fig. 4, for the purpose of giving more power or purchaseto the holding devices e c when the jaws are held for larger drills thanwhen the lsaine are held in position for smaller drills, it beingevident that a greater proportion of power is required for holdinglarger than for holding smaller pieces, and especially, also, in usingthem 5 and it being also evident that the more power is obtained thestraighter the groove d. The pins e are screwed into the shell, asindicated. rlhe two pins pertaining to each jaw stand at an angle toeach other or' about ninety degrees, more or less, as indicated in Fig.3. Then the jaws are in the position shown by full lines in Fig. S-thatis to say, for holding the largest-sized drill to which they arefitted-they can be exactly centered, if found not to be so, by turningone of the pins c more inward and relieving the other proportionately,and thereby slightly turning each For this reason, being able jaw in itssocket.

to adjust the jaws and centering the saine, l prefer to use two pins, e,for each jaw, although I may produce a substantial and reliable chuck byhaving but one pin, e, for each jaw. It is also clear that, instead ofgrooving the jaws and having the pins c in the shell, substantially thesaine results will be reached by grooving the inner faces of theshell-sockets, and providing projecting pins or feathers on the jaws;and I do not confine myself to either construction.

What I claim as my invention isl. The improved drill-chuck, consistingof a shell, A,partlycylindrical jaws C C, adjusting-screw B, and or' thepins c to tit the spiral grooves d, substantially as herein shown anddescribed.

2. A spiral groove, d, for the jaw of a drillchuck, when made straightertoward the outer and more spira-l toward the inner end, sub- Witnesses:

A. V. BRrEsEN, F. V. BRIESEN.

